Transit riders often feel like sardines in a can, but advertisers see them more as fish in a barrel — a captive audience with nowhere to run from the claws of commerce. Once upon a time, messages took the passive form of an ad panel. Lately they've become more invasive: "smell-vertisements" at bus stops, virtual retailers perched on the platform, even the names of stations themselves.

They're coming for your ears, too, though that might not be a bad thing.

Since 2008, a Dayton-based company called Commuter Advertising has been partnering with U.S. transit agencies to play ads over bus speakers before stop announcements. With the recent addition of Lexington, Kentucky, the company now reaches 11 metro areas across the country, including Pittsburgh, Tampa, and Cincinnati. They don't just have riders cornered; they have the whole market.

"We're the only company in the world who can do this right now, or who knows how to do it," says spokeswoman Sam Parker.

By tapping into the GPS systems that trigger stop announcements in most city buses, Commuter Advertising can target its audio ads to specific routes. If the No. 8 bus passes a McDonald's at First and Main, for instance, riders might hear an ad for a McRib special. The company also produces time-based ads as well, which play at certain hours across the whole fleet.

On paper, the idea seems like a win for everyone. (Though, what doesn't?) Advertisers can reach consumers at hand-picked times and places. Transit authorities bag some extra operational revenue without dipping into public pockets. Commuters avoid fare hikes and service cuts in exchange for just a tiny sliver of their soul.

The payoff varies by city. While Commuter Advertising doesn't release its revenue figures, Ryan Holeywell of Governingrecently reported that Champaign, Illinois, has earned about $150,000 from its audio ad partnership since 2009. Not a boom, for sure, but not much of a risk, either, because the company offers its service zero-cost to transit providers and will even compensate them if expenses are incurred.

"We want to make sure they're not spending any resources or money on the program — all they're doing is generating revenue from it," says Parker.

Despite these benefits, plenty of commuters still throw up their hands at the thought of yet another commercial intrusion. Boston has considered the program more than once in recent years for its MBTA buses but hasn't bitten, with officials reportedly wary of irritating riders. (Parker says the company maintains an ongoing relationship with the MBTA.)

Commuter Advertising does its best not to overwhelm the airwaves. (The company was founded by two regular transit commuters, after all, during a serendipitous trip on the Chicago El.) The audio ads never last more than 15 seconds, and they only run at 8 to 20 percent of all transit stops, which means every fifth time the door opens at most.

"Our goal is never to inundate riders with ads," says Parker. "We maintain a low frequency and we also keep track of volume levels."

What transit commuters worry about is the slippery slope. Print ads are no problem until riders find themselves standing at a bus stop transformed into a Dunkin' Donuts oven. Station names are fine to sell unless the system map becomes geographically meaningless. Tame audio ads are likewise acceptable — it's the idea that one day platform loudspeakers will play them non-stop that frightens riders.

As things stand, though, audio bus ads seem to reside at the tolerable end of the transit marketing spectrum. Riders can always wear headphones, and audio campaigns might even prompt transit agencies to fix their habitually busted speaker systems. A little annoying? Sure. Demeaning or intolerable? Hardly. If the money is right, and the approach respectful, they might even be the responsible choice.

About the Author

Eric Jaffe is a senior associate editor at CityLab. He writes about transportation as well as behavior, crime, and history, and has a general interest in the science of city life. He's the author of A Curious Madness (2014) and The King's Best Highway (2010), and lives in New York.